Resource-sparing Post-mastectomy Radiotherapy in Breast Cancer

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This study compares two different field set-ups in patients with breast cancer following a breast resection (mastectomy). These two set-ups are as follows: arm a - radiotherapy to the chest-wall only, and arm b - radiotherapy to the chest-wall and the supraclavicular fossa.

Patients in both treatment arms will receive radiotherapy with a shortened fractionation schedule.

Study hypothesis: irradiation of the chest-wall only is not inferior to irradiation of the chest-wall and supraclavicular fossa in terms of loco-regional control, survival and treatment toxicity.

Condition or disease

Intervention/treatment

Phase

Breast Cancer

Radiation: RadiotherapyRadiation: Irradiation of the chest-wall and supraclavicular fossa

Phase 3

Detailed Description:

Post-mastectomy radiotherapy (PMRT) substantially reduces the risk of loco- regional failure as shown in several studies and meta-analyses. Two large trials for pre-menopausal node-positive breast cancer patients treated with mastectomy and chemotherapy showed that PMRT not only reduced loco- regional failure rates but also improved disease-free and overall survival rates.

Although the benefit of PMRT is clear, the optimal volume of tissues to be covered by the radiotherapy fields is controversial. Since the chest wall is the most likely location of recurrence, there is uniform consensus that the chest wall should be irradiated. However, areas of controversy exist regarding irradiation of the regional lymph nodes (axillary, supraclavicular and internal mammary lymph nodes), optimal radiation dose, and dose-fractionation.

If equivalent results could be achieved by omitting irradiation of the supraclavicular region in patients receiving adjuvant systemic therapy, this will simplify and expedite treatment in this patient population. Furthermore, the use of a shortened fractionation schedule of 40 Gy in 15 fractions (2.67 Gy per fraction) over 3 weeks which has been used in the UK and Canada for post-mastectomy patients for several decades will shorten the duration of treatment by reducing the number of patient visits for radiotherapy and increase the number of patients who can be treated. Treatment will be more convenient for patients and a reduction in the number of treatments could result in savings for strained health care systems.

This is a randomized comparison of two different radiotherapy field set-ups for post-mastectomy treatment of locally advanced breast cancer. Patients who have undergone modified radical mastectomy including axillary lymph node dissection will be randomized to receive one of two radiotherapy treatment arms, A and B following the completion of adjuvant chemotherapy. The radiotherapy for treatment Arm A consists of irradiation of the chest wall only while Treatment Arm B includes irradiation of the chest wall and the ipsilateral supraclavicular field. Patients on both treatment arms will receive radiation with a shortened fractionation schedule. Patients will be evaluated for local control, regional control, survival and treatment toxicity.

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Note: MRM should have been performed at maximum 3 months prior to the start of adjuvant chemotherapy.

Special Note: Patients who have not received adjuvant chemotherapy will be required to receive adjuvant chemotherapy as per Appendix 3 prior to study entry and initiation of radiotherapy must allow for the full recovery of blood counts (WBC > 3.0 x 109/L, Granulocytes > 1.5 x109/L and platelets > 75 x 109/L MRM should have been performed within 3 months prior to the start of adjuvant chemotherapy.

Patients must have received adjuvant chemotherapy according to one of the two regimens found in Appendix 3.

Negative surgical margins by histopathology at the time of MRM. Note: Negative surgical margins means that there are no cancer cells at the inked margin of resection or otherwise at the margins of the mastectomy specimen.

The following indicators in the histological samples must be known :

Tumor size

Tumor site (quadrant, central, axillary tail)

Presence of extensive intraductal component (EIC)

Estrogen and Progesterone Receptor Status and the method of staining and detection.